TEHRAN, May 16 (Xinhua) -- With three days away from voting day, two major candidates for the presidential post have withdrawn their bid, leaving the race open for four others.

On April 21, out of 1,636 registered candidates, six qualified to compete for the four-year presidential term, including three principalists, better known as conservatives, as well as two centrists and one reformist.

On Tuesday, Iran's reformist Vice President, Eshaq Jahangiri, announced his withdrawal from the race in order to back incumbent President Hassan Rouhani, urging all his supporters to vote for Rouhani.

Tehran's Mayor Mohammad Baqer Qalibaf, a conservative candidate, said in a statement on Monday he withdrew from the presidential race to back another conservative candidate, Ebrahim Raisi.

The following is a biography of the four presidential candidates:

HASSAN ROUHANI

Rouhani was born on November 12, 1948.

He was elected to parliament, better known as the Majlis, and served five consecutive terms from 1980 until 2000.

He held a variety of posts related to national security during the Iran-IraqWar from 1980 until 1988.

He served as a High Council member for the country's National Defense and as commander of Iran's air defenses.

In 1989, he was appointed as secretary of the Supreme National Security Council, a post he occupied under centrist president Akbar Hashemi Rafsanjani from 1989 until 1997, as well as reformist president Mohammad Khatami from 1997 until 2005.

Between 2003 and 2005, Rouhani led the Iranian delegation in negotiations with the International Atomic Energy Agency (IAEA) and the international community regarding Iran's nuclear energy program.

He also stated he supports restarting international negotiations regarding Iran's nuclear program hoping for reduced sanctions against Iran.

In Sept. 2013, he launched a diplomatic campaign to improve Iran's engagement with the west.

Rouhani's pledge to restart international negotiations regarding Iran's nuclear activities was fulfilled in early Nov. 2013 with the reopened talks between Iran and six major world powers.

An agreement was reached in July 2015 requiring Iran to reduce its nuclear stockpile and allow inspections of its nuclear facilities in exchange for a gradual reduction of sanctions.

As for domestic policy, he encouraged personal freedom and free information access, improved women's rights by appointing a female foreign ministry spokesperson and improved the economy by reducing inflation and increasing its growth rate.

EBRAHIM RAISI

Ebrahim Raisi was born on December 14, 1960.

In 1981, he was appointed as Iran's Karaj city prosecutor.

After four months, he was appointed as Prosecutor of Hamadan Province.

In 1985 he was appointed as Tehran's deputy prosecutor.

Three years later, he received special provisions from the late founder of the Islamic Republic Ayatollah Ruhollah Khomeini to address legal issues in provinces like Lorestan, Semnan and Kermanshah.

Following Khomeini's death and election of Khamenei as the new Supreme Leader, Raisi was appointed as Tehran's prosecutor.

He held the office for five years from 1989 to 1994 and in 1994, while still Tehran's prosecutor, he was appointed as head of the General Inspection Office.

From 2004 until 2014, Raisi served as Iran's first deputy chief of justice.

He was later appointed as Iran's Attorney-General in 2014, a post he served in until 2016.

Raisi was subsequently appointed by Iran's Supreme Leader on March 7, 2016 as the custodian and chairman of the Shrine of Shiite Imam Reza in the northeastern Iranian city of Mashhad.

Raisi voiced a need for a "fundamental change in the executive management of the country" and a government that "fights poverty and corruption."

MOSTAFA AGHA MIRSALIM

Mostafa Agha Mirsalim was born on June 9, 1947.

He is a conservative Iranian politician.

Mirsalim served as the national police chief following the Iranian revolution in 1979.

He was recommended by then president Abulhassan Banisadr in July 1980 as a compromise prime ministerial candidate acceptable to both Banisadr and the then Islamic Republican Party dominated Majlis.

From 1979 to 1982, he served as the Interior Ministry's socio-political deputy, then from 1981 to 1989 Mirsalim became advisor to then president Ayatollah Ali Khamenei.

Then in 1989 until 1993 he was advisor to president Akbar Hashemi Rafsanjani.

In 1994, Mirsalim was appointed as Minister of Culture and Islamic Guidance, later appointed to the Expediency Discernment Council.

Over the past years, he became affiliated to the Islamic Coalition Party and Islamic Republican Party.

Currently he is assistant professor of mechanical engineering at Tehran's Amirkabir University of Technology.

MOSTAFA HASHEMITABA

Mostafa Hashemitaba was born in 1946 and is known as an Iranian centrist politician.

He served as Iran's minister of industries from 1981 until 1982 under President Mohammad-Ali Rajaei.

He was also vice president and head of the Islamic Republic of Iran's National Olympic Committee from 1994 until 2001 under moderate president Akbar Hashemi Rafsanjani and reformist president Mohammad Khatami.

He was a candidate in the Iranian presidential election in 2001, coming in at 10th place.

He said dealing with unemployment as well as foreign and private investors should all be encouraged and supported, particularly in the tourism sector.

He has also pledged to fight economic corruption.

On Saturday, he said he will vote for President Rouhani in the upcoming May 19 presidential elections.